Mercury-meter.



D. G. JACKSON.

MERCURY METER.

APPLIOATION FILED 11116.5, 190?.

Patented Jan. 7, 1913.

mania) 2W C kajtsan fl Z #07 213 f DUGALD C. JACKSON,

0]? BOSTON, MASSACHUSETTS.

MERCURY-METER.

Specification of Letters Patent.

Patented Jan. '7, 1913.

Application filed August5, 1907. Serial No. 387,019.

To all whom it may concern:

Be it known that I, DUGALD C. JACKSON, citizen of the United States, residing at Boston, in the county of Suffolk and State of Massachusetts, have invented a certain new and useful Improvement in Mercury- ,eters, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

y invention relates to wattmeters, par ticularly to mercury wattmeters, its object being to produce a meter of this kind which will accurately and efliciently register watts when used with alternating current circuits.

When a mercury wattmeter is used for measuringalternating current, many conditions must be compensated and adjusted for, as for instance, frequency conditions or phase relations. To be commercially suocessful the meter must be constructed to automatically compensate and adjust for frequency changes and must automatically take care of the phase relationships and variations. Friction and its varying value must also be adjusted for. The meter must be adapted to meet all the varying conditions so that it can be accurate in its registration throughout a wide range of such variations of conditions. The mechanical construction and arrangement of the various meter parts play a very important part in the accomplishment of accurate registration through a wide range, the desire being also that the physical meter be not too bulky or of too much weight, but should be comparatively small and compact, as light as possible and neat in appearance, and the object of my invention is to accomplish all these desired features ofoperation and construction.

My invention will be better understood if described in connection with the accompanying drawings which represent one embodiment of the invention and in which- Figure l is a diagrammatic view, showing the arrangement of the various compensating and adjusting devices of the meter; 'Fig. 2 is a diagrammatic view, showing a modification in the arrangement of the compensating and adjusting devices.

The width of the mercury chamber should be as small as possible,but it should be of sufficient width mechanical clearance and to prevent undue "flux to pass through 'netic circuits or which may to allow for reasonable.

friction of the mercury. To attain the best results, the edges of the magnetic plates should be clear of insulating material, the object being to have the magnetic gap as small .as possible so as to get the magnetism through the armature with the least expenditure of energy. The armature is given the cup-shape shown in order to provide for greater surfacefor the magnetic without increasing the diameter of the armature.

Fig. 1 shows the circuit arran ements for the meter and its connection with the circuit whose wattage is to be measured. The magnetic core 17 of the potential winding of the meter is surrounded by frame 16, so conformed that its lower portion constitutes a cup for containing mercury in which the armature 26 is rotatably supported. The compensating and adjust-' ing mechanisms are here shown more or less diagrammatically sure transformer and a series transformer 51. The primary winding 52 of the pressure transformer is connected across the limbs a, b,

1n clrcuit with the energizing winding '54 surrounding the magnetic core of the meter. This transformer changes the line pressure to a suitable voltage for operating the meter, and the transformer is also arranged to compensate for changes in frequency. This compensation is obtained by means of the tongues 55, 56, which form a leakage path between the primary and secondary magof the transformer, these tonguesbeing separated by the air gap 57. The tongues are also surrounded by the winding 58 which may be short-circuited include in circuit the extra resistance 59. The transformer core is built up of laminations which are pr'efer ably so arranged that the air gap 57 may conveniently be varied in order to adjust for the proper compensation effect, as shown in Figs. 1 and 2. By getting the, correct relation between the length of the air gap and, the number of turns and resistance of 1 the compensating winding 58, compensation for 'requency is obtained by the least expenditure of energy. The effect of friction iscompensated for by means of current from a winding 60 afiected by the magnetic circuit of the primary of the a magnetic V and comprise a presof the circuit to be measured, while the secondary wlnding 53 is connected inc -The circuit 61 including this transformer.

lIlClJlCl'GS the met er core 61' on which are the windings 62, these windings and the armature being included serially in the line limb b, the circuit being from the line limb b .to the outer electrodes, through the mercury chamber and armature to the central electrode, then through the windings 62 and back to the line limb b. The secondary 63 of the transformer 51 is a very low pressure, low resistance winding and may be a singleloop of copper. ne terminal of thissecondary winding connects with the outer electrodes and the other terminal connects with the central electrode, the secondary current, therefore, also passing through the mercury chamber and arma ture. such as, will produce an air gap 64, and these laminationsare preferably arranged so'as to be adjustable whereby the length of the air gap may be varied. The current from the transformer is combined with that of the line so as to give a resultant current through the armature which. is in phase with the magnetism passing through the armature when the load is without reactance, this being a condition for the accurate and satis- I factory operation of the meter. The transformers are supported in any convenient position within the meter frame.

V minishes, but the The operation of the meter and the com pensating, adjusting mechanisms is as 01- lows: The conjoint effect of the magnetic flow transversely through the armature, and the current flow radially through the mercury and armature is to cause rotation of the armature andof the indicating mechanism connected therewith. W'hen'the meter is used on alternating current, the compen sating devices are necessary, and with stand ard frequency a definite amount of flux will pass through the magnetic circuit of the pressure transformer 50 and a definite part of this magnetic flow goes through the leakage path and air gap. If the frequency of the circuit rises, there is a tendency for the meter to take less exciting current on account of the changes in the inductive conditions, and the meter thus tends to run slower. When the frequency rises, the amount of flux through the transformer dishort-circuited winding is constant in its effect and chokes back the so that the secondary same amount of flux'during any frequency,

of the transformer will get more than its proportionateshare of the flux than it would with the lower frequency, and the pressure at the terminals of the secondary winding and consequently the presterminal of the" cir- The laminations of the core 61 are a 51, being through the 'quency, falls, current to pass through it and thus withdraws current from the armature. ltional current is thus furnished the armature when the magnet-ism decreases owing to frequency change and less 7 current is sure of the energizing meter winding rises,

and if the compensating transformer 1s properly adjusted, the meter speed will not be affected. If the frequency on the other hand, should be diminished, the secondary terminal pressure will correspondingly diminish. By proper adjustment, therefore,

of the pressure transformer,

the change of pressure of the secondary winding is made to overcome the normal change in exciting current of the meter with change'of frequency, and the speed of the meter remains constant for uniform-loads.

To cause the meter to register properly under varying conditions of pressure of the main circuit, the magnetic circuits ofthe meter should be designed so that for increase or decrease of pressure across the circuit,

the magnetism passing through the armature will increase or decrease so as to keep the meter operating at its correct constant,

namely, 4 7

Watts measured whether the pressure remains constant or varies between reasonable l1m1ts. This is done by having the magnetic densities in the pressure transformer and the meter so that they will be on the portions ofthe magnetization curve which will give this desired variatlon of flux through, the armature.

Another method for obtaining frequency compensation is illustrated in Fig. 2, in

which an inductance coil 69 is associated.

with the primary of the series transformer shown as connected in-bridge of the primary of, the transformer together with the meter armature. lVith this arrangement when the frequency rises, the inductance of 69 permits lesscurrent to pass through the coil, thus sending more current armature, and when the frethe inductance permits more Addiavailable for the armature when the magnetism increases owing to frequency change,

and by correctly proportioning the inductance, it can be made to compensate correctly for any frequency error.

Many other changes and variations may be made in the construction and arrangement of the meter parts and circuits without departing from the scope of the invention, and I should not be limited to, the part-icular arrangements shown and described. I desire to secure the following claims by Letters Patent;

-' 1. In a mercury meter, the combination of a magnetic frame providing a mercury chamber, an armaturefplvoted to "be rotatable within said chamber, ing for the magnetic frame, a transformer having a winding connected with the magnetizing winding and having another winding adapted for connection with the alternating current circuit to be measured, said transformer having devices compensating for frequency changes.

2. In a mercury .meter, the combination of a magnetic frame providing a mercury chamber, an armature pivoted to be rotatable within said chamber, a magnetizing winding for the magnetic frame, a transformer having a winding connected with the magnetizing winding and another winding adapted for connection with the circuit to be measured, a. magnetic leakage path for the transformer, and a closed circuit winding on said leakage path, said closed circuit Winding and said leakage path affording means for adjustingand compensating for frequency changes.

3. In an alternating current mercury meter, the combination of a magnetic frame providing a mercury chamber, an armature pivoted to be rotated within said chamber, a magnetizing winding for the magnetic frame, a transformer having a winding connected with the magnetizing winding and having another winding adapted for connection with the circuit to be measured, a

magnetic leakage path for the transformer air gap, and an auxilmagnetic leakage path, air gap and auxiliary having an adjusted iary winding for the said leakage path,

winding affording a means for adjusting for frequency variation.

4. In an alternating current wattm-eter, the combination of a frame providing-a mercury chamber, an armature adapted to rotate within the cham ber, a magnetizing winding for the magnetic frame, a pressure transformer having a winding adapted for connection with the circuit to be measured and a secondary winding connected with the magnetizing winding, a magnetic leakage path for the transformer having an adjustable air gap and a short circuited auxiliary winding for said. leakage path, said leakage path, air gap and short circuited winding cooperating with the magnetic flow of the transformer to cause the current flow through the secondary winding which, will produce a V magnetic flow through the armature proportional to the pressure of the circuit to be measured, and means for causing cur rent flow through the armature proportional to the current flow through the main circuit. 5. In an alternating current mercury wattmeter, the combination of a magnetic frame providing a mercury "chamber, an armature adapted to rotate within the chamber, a magnetizing winding for the magnetic frame, a pressure transformer having a magnetizing windframe providing magnetic a winding adapted for connection with the circuit -to be measured and a secondary Winding connected with the magnetizing winding, a magnetic leakage path for the transformer having an adjustable air gap, a short-circuited auxiliary winding for said leakage path, said leakage path, air gap and short-circuited winding cooperating with the magnetic flow of the transformer to cause current flow through the secondary winding which will produce a magnetic flow through the armature proportional to the pressure of the circuit to be measured, and means for causing current flow through the armature proportional to the current flow through the main circuit.

6. In an alternating current mercury wattmeter, the combination of a magnetic a mercury chamber, an armature adaptedto rotate within the chamber, a magnetizing winding for the magnetic frame, a pressure transformer having a winding adapted for connection with the circuit to be measured and a secondary winding connected with the magnetizing winding, :a magnetic leakage path for the transformer having an adjustable air gap,

a short-circuited auxiliary winding for said leakage path, said leakage path, air gap and short-circuited winding cooperating with the magnetic flow of the transformer to cause current flow through the secondary winding which will produce a magnetic flow through the armature proportional to the pressure of the circuit to be measured, and

a series transformerincluded in the main circuit, the windings of said series transformer being associated with the armature to cause current flow therethrough proportional to the current flow through the main circuit. r 7. In an alternating current mercury wattmeter, the combination of a magnetic frame providing a mercury chamber, an armature adapted to rotate within the cham ber, a magnetizing winding for the magnetic frame, a pressure transformer having a winding adapted for connection with the circuit to be measured and a secondary winding connected with the magnetizing winding, a magnetic leakage path for the transformerhaving an adjustable air gap, a short-circuited auxiliary winding for said leakage path, said leakage path, air gap and short-circuited winding cooperating with the magnetic flow of the transformer to cause current flow through the secondary winding which will produce amagnetlc flow throiwh the armature ro ortional to the e pressure of the circuit to be measured, means for causingcurrent flow through the armature proportional to the current flow through the main circuit, and friction compensating means comprising a circuit which serially includes the armature and by in;-

: cuit with which the meter is connected;

- 9. In an alternating current mercury wattmeter, the combination of a magnetic frame providing a mercury chamber, an armature pivoted to rotate within said chamber, a magnetizing winding for the magnetic frame, means for causing current flow through the magnetizing winding proportional to the pressure in the circuit wlth i through the main circuit to be measured.

which the meter'is connected, a series transformer, a primary transformer included serially in the main circuit with the armature, and a secondary winding upon the same core as the primary winding and connected. in bridge of the transformer having an adjusted air gap whereby to bring the phase of the current through the armature and the phase of the magnetic flow through the armature into the same rent and pressure of the main-circuit.

10. In an alternating current mercury armature, said watt meter, the combination. of a magnetic ;the combination of an armature and a field L windi g} & transformer frame providing a mercury chamber, an armature pivoted to rotate within said chamber, means for causing a magnetic flow through the magnetic frame and armature roportional to with which the meter is connected, a transformer, a primary winding for; the transformer connected serially inthemain circuit with the armature, a secondary winding for the transformer bridged about the armature, means providing compensating current flow through the armature to compensate for friction variation, and means for mainmeasured.

taining practically constant the effective 'magnetic flow through the magnetic frame for variations in frequency of the current 11. In a mercurywattmeter, the combination of an armature, 'a magnetic frame providing a mercury chamber for the armature and adapted for generating magnetic flux through the armature, a magnetizing wind-f ing for energizing the magnetic frame, a having a primary winding adapted for connection withv a constant potential circuit, said transformer having one secondary winding arrangedto furnish curing winding for rwlnding for said series 1 the combination of an armature, a field frame for the armature, means gization of the field frame and magnetic flux l pr oportionalto the ing current main ing a primarywinding included in the mam icircuit, said main circuit also including the E armature, ithe same core as the primary winding pargalleled with a portion of the including the armature.

relation as the cur-V the pressure of the circuit windings, secondary windings to furnish current at a pressure independent of thefrequency'but dependent on the combination causing a magnetic flow through the arma-' rent to the armature at a pressure independent of the frequency but dependent upon the pressure applied to the primary winding, another secondary winding for the transformer arranged to furnish current to the magnetizing winding at a pressure dependent upon the frequency, and means for causing current flow through the armature proportional to the current flow through the constant potential circuit.

12. In an alternating current wattmeter, the combination of an armature adapted to rotate, a magnetic frame for causing magnetic flux through the armature, a magnetizthe magnetic frame, a pressure transformer having a primary winding adapted for connection with the alternating 1 current circuit to be measured andhaving a secondary winding connected with the mag- 1 netizing winding,a second secondary winding for the transformer for supplying cur- 1 rent flow through the armature, and means 3 for causing current flow through the armaflow ture proportional to the current 13. In an alternating current wattmeter,

for causing enerpressure of an alternatcircuit, a transformer hayand a secondary winding upon main clrcuit 14. In analternating current wattmeter,

having a winding l'included in the maln circuit, said main circuit also" including one circuit of the meter, .and a the primary winding paralleled with a porsecond winding upon'the same core as tion of the main circuit including the armature. r

15. An alternating current meter with a field winding and an armature, a trans-- former, a primary winding,

two secondary means for causing one of said the pressure applied to the primary winding and for causing the other secondary winding to furnish current dependent upon the frequency, and electrical connections from said secondary windings to the circuits of the meter.

16. 'In an alternating current wattmeter, of an armature, means for stantially constant effective'magnetic flow through the armature for variations in frequency of the current measured.

17. In an alternating current Watt meter, the combination of an armature, inductance means for maintaining a substantially co11- armature in phase with the magnetic field 10 thus produced.

In Witness whereof, I hereunto subscribe my name this 20th day of July A. D., 1907.

DUGALD O. J AOKSON Witnesses:

CARRIE M. BARNES, MABEL F. JACKSON.

Gopies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). 0.? 

